1. Field of the Invention
This invention relates to a process for the production of fertilizers provided with biologically active agents and the fertilizers produced thereby. More specifically, a process is provided by which a granular or semi-granular fertilizer can be formed which may further incorporate various organic agents, particularly in a folial fertilizer form.
2. Description of the Prior Art
It has long been the practice to artificially enrich the nutrients available to crops to enhance and accelerate their yield by application of fertilizer to the crops, particularly to the ground or water supply for the crops. Similarly, fertilizers are commonly used to improve the growth of plants desired for their aesthetic characteristics. Recently, industry attempts have focused on the provision of a fertilizer which is applied to and absorbed through the leaves of the plants, or a folial fertilizer, as a more efficient, and in the long run, less expensive method of fertilizing. Such folial fertilizing methods also lend themselves to the introduction or incorporation of biologically active agents, particularly growth regulators to further stimulate growth. As a result, those of skill in the industry have also focused on developing means to provide a fertilizer including such agents in a granular or semi-granular form. Unfortunetly, such attempts have met with numerous problems.
Among the most important of the problems encountered is the difficulty in providing a fertilizer with all the necessary nutrients in a form useful, particularly as a folial fertilizer. The formation of granular, or semi-granular fertilizers, which can be discretely dispensed with the aid of water, has long been sought, but rarely achieved. Frequently, attempts to provide such fertilizers have resulted in products which quickly separate and lose their integrity or are non-uniform to begin with.
Further problems encountered in the effort to provide granular, folial fertilizers is the difficulty in binding the nutrient to the core of the granule. Although traditionally a binder in the nature of a wax or oil is employed, as described in U.S. Pat. Nos. 3,295,950 and 3,580,715, these are unsuitable for folial fertilizers, as leaf absorption requires the fertilizer components to be water soluble.
One alternative is described in U.S. Pat. No. 3,867,124, which employs a urea-ferrous sulphate complex as a binder for the nutrients about core prill. However, urea is a highly concentrated nitrogen source, and application of urea in a folial fertilizer may cause nitrogen burning, or phytotoxicity.
Another problem encountered in the provision of biologically active agents is that many of these agents are denatured or "killed" at relatively low temperatures, particularly those agents which are, or based on, complicated protein structures. As many of the prior art attempts to form granular fertilizers, with or without biologically active agents, have employed relatively high heats, above 200.degree. F., these processes cannot be used to form a fertilizer incorporating a biologically active agent of this type.
Accordingly, there persists an industry-wide need to provide a granular or semi-granular fertilizer, particularly a folial fertilizer prepared without a binder, which may further incorporate one or more biologically active agents.